Asphalt is the oldest material conferring impermeability used by man. The components of asphalt may be separated into asphaltenes and maltenes. Asphaltenes are defined as a fraction having a black colouring insoluble in n-heptane, whereas maltenes are constituted by saturated compounds, aromatic compounds and resins, soluble in n-heptane. The percentage composition of asphaltenes, maltenes and other constituents has a significant effect on the viscoeiastic properties of asphalts and, consequently, on the performance of road-paving mixtures.
The use of asphalts modified by polymers to improve the performance of paving asphalts has been observed throughout time properties of the asphalt matrix modified by polymers depend directly on the characteristics and concentration of such polymers and also on the nature of the asphalt matrix.
Currently there is a great variety of polymers being utilised in the modification of asphalt matrices. However the greatest obstacle to the use of modified asphalt matrices in practical paving is their tendency to phase separation due to poor compatibility between the polymer and the asphalt matrix.
In addition to current concern with the use of environmentally-safe products, it is also necessary to develop asphalt coatings having a lower temperature than the traditional temperature, plus greater resistance to permanent deformation, greater light reflection, and such products should provide support and safety for users in tunnels, on bridges and in curves on roads, enhancing the concentration of drivers.
The state of the art in respect of pigmentable compositions is described below.
U.S. Pat. No. 5,389,137 granted on Feb. 14, 1995 to Bayer AG, describes a process for asphalt colouring by compositions of inorganic pigments with oils having a kinematic viscosity at 40° C. from 1.6 to 1500 mm2/s, or with waxes and paraffins having a softening point lying between 50° C. and 180° C.
U.S. Pat. No. 5,484,481, granted on Jan. 16, 1996 to Bayer AG, presents a process for colouring construction materials, such as concrete or asphalt, using inorganic granular pigments mixed with binders derived from petroleum or synthetic oils, or biodegradable oils of vegetable and animal origin, having a kinematic viscosity in a band from 1.6 to 1500 mm2/s at 40° C. and inorganic pigments.
Patent application US 20030047116, published on Mar. 13, 2003, describes pigment compositions in a homopolar medium with dispersants for colouring bitumens and asphalts.
It transpires that as the state of the art utilises petroleum residues having a high content of asphaltenes and in addition utilises environmentally-dangerous diluents, the development is necessary of a product not possessing the disadvantages of the state of the art.